Summary: Abstract1
The light reflected from a surface depends on the scene
geometry, the incident illumination and the surface mate-
rial. A novel methodology is presented which extracts
reflectivity information of the various materials in the
scene independent of incident light and scene geometry. A
scene is captured under different narrow-band color filters
and the spectral derivatives of the scene are computed.
The resulting spectral derivatives form a spectral gradient
at each pixel. This spectral gradient is a material descrip-
tor which is invariant to scene geometry and incident illu-
mination for smooth diffuse surfaces. Spectral gradients
can discriminate among smooth dielectrics with different
reflectance properties independent of viewing conditions.
1. Introduction
The starting point of most computer vision techniques
is the light intensity reflected from an imaged scene. The
reflected light is directly related to the geometry of the
scene, the reflectance properties of the materials in the
scene and the lighting conditions under which the scene